A METHOD FOR CALCULATING DYNAMIC BREAST CENTRE OF MASS DURING RUNNING

This study aimed to develop a novel method for calculating breast centre of mass (COM) during running for use in musculoskeletal modelling. Magnetic resonance imaging (MRI) scans and kinematic data were collected from a female participant running at 2.6 m·s-1. A breast surface marker array was used to calculate the COM of 16 segments, based upon tissue composition from the MRI scan. The motion of the surface markers were used to calculate breast COM position during running. Breast COM was more superior, medial and posterior than the nipple marker. Breast COM range of motion was lower (~50%) in all directions during running when compared to the nipple marker. Results suggest that the localised breast deformation is the key factor in calculating breast COM during running

FORCE ASYMMETRY DURING ISOMETRIC CONTRACTIONS FOLLOWING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

The aim of this study was to compare isometric strength asymmetry in participants that have previously undergone anterior cruciate ligament (ACL) reconstruction and a healthy control group. Three-dimensional force data (1000 Hz) were collected from 21 ACL (3.2 ± 1.8 years post-surgery) and 21 control participants during maximal isometric contractions. Peak knee flexion force displayed significant asymmetry differences between groups, with ACL participants showing greater asymmetry (7.6 %) than the control group (0.1 %). No significant asymmetry differences were found between groups for peak extension, adduction and internal rotation force. Results suggest that following ACL reconstruction and rehabilitation, external force production during knee flexion is significantly less on the affected side than the uninjured side, which has implications on rehabilitation monitoring

Functional phases and angular momentum characteristics of Tkatchev and Kovacs

Understanding the technical requirements and underlying biomechanics of complex release and re-grasp skills on high bar allows coaches and scientists to develop safe and effective training programmes. The aim of this study was to examine the differences in the functional phases between the Tkatchev and Kovacs skills and to explain how the angular momentum demands are addressed. Images of 18 gymnasts performing 10 Tkatchevs and 8 Kovacs at the Olympic Games were recorded (50 Hz), digitised and reconstructed (3D Direct Linear Transformation). Orientation of the functional phase action, defined by the rapid flexion to extension of the shoulders and extension to flexion of the hips as the performer passed through the lower vertical, along with shoulder and hip angular kinematics, angular momentum and key release parameters (body angle, mass centre velocity and angular momentum about the mass centre and bar) were compared between skills. Expected differences in the release parameters of angle, angular momentum and velocity were observed and the specific mechanical requirement of each skill were highlighted. Whilst there were no differences in joint kinematics, hip and shoulder functional phase were significantly earlier in the circle for the Tkatchev. These findings highlight the importance of the orientation of the functional phase in the preceding giant swing and provide coaches with further understanding of the critical timing in this key phase

THE INFLUENCE OF MOOD DURING TREADMILL RUNNING ON BIOMECHANICAL ASYMMETRY OF THE LOWER-LIMB

This study aimed to investigate if mood effects lower-limb biomechanical asymmetry during running. Twenty runners (13M, 7F; age 22-58 years), performed four 3-minute runs at their 5km pace (3.3 ± 0.3 m/s), preceded by a mood questionnaire. Baseline data were captured, followed by randomised mood conditions: anger, happiness, and sadness; elicited with film clips and music. Symmetry angles used for analysis. In the sadness condition, compared with baseline, biomechanical asymmetry significantly increased (p \u3c .05) by 3.7% at ground contact for hip abduction, and at toe-off for knee abduction by 0.6% and internal rotation by 1.1%. Toe-off plantarflexion asymmetry decreased by 2.2% with anger, compared to baseline. Happiness did not appear to affect asymmetry. Results suggest sadness may increase asymmetry and associated overuse injury risk, and anger may facilitate symmetry

A biomechanical comparison of initial sprint acceleration performance and technique in an elite athlete with cerebral palsy and able-bodied sprinters

Cerebral palsy is known to generally limit range of motion and force producing capability during movement. It also limits sprint performance, but the exact mechanisms underpinning this are not well known. One elite male T36 multiple-Paralympic sprint medallist (T36) and 16 well-trained able-bodied (AB) sprinters each performed 5–6 maximal sprints from starting blocks. Whole-body kinematics (250 Hz) in the block phase and first two steps, and synchronised external forces (1,000 Hz) in the first stance phase after block exit were combined to quantify lower limb joint kinetics. Sprint performance (normalised average horizontal external power in the first stance after block exit) was lower in T36 compared to AB. T36 had lower extensor range of motion and peak extensor angular velocity at all lower limb joints in the first stance after block exit. Positive work produced at the knee and hip joints in the first stance was lower in T36 than AB, and the ratio of positive:negative ankle work produced was lower in T36 than AB. These novel results directly demonstrate the manner in which cerebral palsy limits performance in a competition-specific sprint acceleration movement, thereby improving understanding of the factors that may limit performance in elite sprinters with cerebral palsy

BREAST MOVEMENT ASYMMETRY DURING RUNNING: IMPLICATIONS ON BREAST SUPPORT

This study aimed to investigate 1) the prevalence and magnitude of breast movement asymmetry, 2) the interaction between static and dynamic breast asymmetry during running and 3) the influence of sports bras on breast asymmetry. Nipple position data were collected from 167 female participants whilst treadmill running and then from a sub-group of twelve participants running in different bra conditions. Breast movement asymmetry was present in 74% of participant during running, with greater resultant static breast position asymmetry for participants that displayed asymmetry whilst running. Asymmetry was most commonly caused (65 - 80%) by greater movement of the left than right breast. Sports bras reduced asymmetry prevalence to as few as 17% of participants in the antero-posterior direction but only 58% in the infero-superior direction

Asymmetry analysis of the arm segments during forward handspring on floor

Asymmetry in gymnastics underpins successful performance and may also have implications as an injury mechanism; therefore, understanding of this concept could be useful for coaches and clinicians. The aim of this study was to examine kinematic and external kinetic asymmetry of the arm segments during the contact phase of a fundamental skill, the forward handspring on floor. Using a repeated single subject design six female National elite gymnasts (age: 19 ± 1.5 years, mass: 58.64 ± 3.72 kg, height: 1.62 ± 0.41 m), each performed 15 forward handsprings, synchronised 3D kinematic and kinetic data were collected. Asymmetry between the lead and non-lead side arms was quantified during each trial. Significant kinetic asymmetry was observed for all gymnasts (p < 0.005) with the direction of the asymmetry being related to the lead leg. All gymnasts displayed kinetic asymmetry for ground reaction force. Kinematic asymmetry was present for more gymnasts at the shoulder than the distal joints. These findings provide useful information for coaching gymnastics skills, which may subjectively appear to be symmetrical. The observed asymmetry has both performance and injury implications